For example, a mass flow controller that is this type of fluid control apparatus includes fluid control units, such as a flow rate sensor and a flow rate control valve, an electric circuit board to send and receive a signal to and from these fluid control units, and a casing to accommodate therein the fluid control units and the electric circuit board, as disclosed in Patent Document 1. The mass flow controller is configured to be connected with a cable to, for example, a user-side information processor via a connector disposed on the electric circuit board.
Recently, thinning of the fluid control apparatus, such as the mass flow controller, is desired for reducing an installation area. Hence, for example, the present inventors have been developing a mass flow controller having an extremely small dimension in a width direction that is a direction orthogonal to a face plate part of the casing.
Owing to the development of the above mass flow controller, a plurality of the mass flow controllers adjacent to each other can be disposed closely adjacent to each other without any clearance therebetween by disposing the mass flow controllers so that the face plates of the casings are opposed to each other. This makes it possible to configure an extremely compact fluid control system.
In order to manufacture a mass flow controller having an extremely small width direction dimension, it is necessary to minimize an clearance between an inner surface of the casing and various types of electronic components, the fluid control units, or the like to be mounted on the electric circuit board, while avoiding any interference therebetween.
Accordingly, for example, arrangement of the electric circuit board and the fluid control units in the width direction of the casing is determined to some extent, so that, for example, the electronic circuit board is disposed at a position shifted from a middle part in a width direction of the casing toward one face plate part or the other. Consequently, a connector mounted on the electric circuit board is disposed shiftedly from the middle part in the width direction of the casing toward one face plate part or the other.
Thus, when the connector is disposed shiftedly from the middle part in the width direction of the casing, a cable-side connector to be connected to the connector is not accommodated within the width of the casing but protrudes beyond the casing. This can cause the following problems. That is, for example, when taking out one of the mass flow controllers disposed adjacent to each other without any clearance therebetween, or when adjacently disposing other mass flow controller between two mass flow controllers, ease of work can become very low when an operation is carried out while the cables are in place, and working efficiency can become very low when the operation is carried out while attaching and detaching the cables one by one.